This placebo-controlled, parallel design, multicenter trial of prednisone in Alzheimer's Disease will test the hypothesis that broad-spectrum anti-inflammatory therapy will suppress brain inflammation, slowing the progression of Alzheimer's Disease. One hundred-fifty subjects will be enrolled at 15 sites and randomized so that half receive prednisone and half receive placebos. Prednisone will be given at an initial daily dose of 20mg for the first month, then tapered to a maintenance dose of 10mg daily to complete one year of treatment. The next four months involve a slow taper period.